German patent application 25 03 118 discloses a moving conveyor or treadmill means according to the WOODWAY system whose endless driven moving conveyor consists of two endless belts that are in parallel with each other and are connected by means of a plurality of tread lamellae which extend in a direction transverse to the running direction. Deflection pulleys around which the endless moving conveyor is guided are seated in the known moving conveyor means at the ends of two shafts arranged one after the other in spaced-apart relationship.
Such lamellar moving conveyors comprise support rollers, in particular ball-bearing support rollers, below the upper side of the moving conveyor.
Moving conveyor means with an even conveyor surface i.e. without gradient (inclination), are used virtually exclusively in rehabilitation centers. By contrast, fitness centers preferably employ moving conveyor means in which the gradient (inclination) of the moving conveyor can be adjusted in any desired manner. To this end the front end of the moving conveyor is lifted whilst the rear conveyor end remains in its original position. As a result of such a height adjustment, the user of such a moving conveyor must run "uphill".
It is important for all moving conveyors because of the safety of the user (hereinafter called "runner"), and in order to guarantee the training success aimed at, that the adjustable conveyor speeds which are carefully predetermined as a rule and preset via control units be observed.
At gradients of about 2% and more, problems arise with respect to the control of the respectively predetermined conveyor speeds, especially in lamellar moving conveyors that are lower in friction than more conventional moving conveyors.
As is generally known a moving conveyor is driven as to its direction in such a manner that the running direction of a runner is opposite to the direction of movement of the upper conveyor side acted upon by the runner.
At gradients of about 2% and more, the introduction of forces into the moving conveyor, which forces are created by the runner pushing his feet off from the moving conveyor, accelerates the conveyor movement, since the push-off forces exerted on the moving conveyor create movement pulses that act in the direction of the conveyor drive. As a consequence, said push-off forces add up to the drive force exerted by the drive means (electric motor) on the moving conveyor, with the effect that the moving conveyor moves faster than intended. Such accelerations of the conveyor movement is a risk potential for runners.
To avoid such an undesired effect, so-called 4-quadrant control units are used for keeping the predetermined conveyor speed constant, the control units controlling the conveyor speed both in the forward direction and the rearward direction with the aid of electric/electronic measuring and control circuits. At gradients of about 2% and more, the moving conveyor must be braked more and more for this purpose so as to guarantee that the predetermined conveyor speed is maintained without the conveyor speed being influenced by the runner.
Such an electric/electronic 4-quadrant control is rather troublesome and considerably increases the production costs of a moving conveyor means with inclination adjustment.